When dynamically linking, a type symbol's name is replaced with a name based on
the SHA1 of the name as type symbol's names can be very long.  However, this
can make a type's symbol name longer in some cases. So skip it in that case.
One of the symbols this changes the treatment of is 'type.string' and that fixes a
bug where -X doesn't work when dynamically linking.

Fixes #16671

Change-Id: If5269038261b76fb0ec52e25a9c1d64129631e3c
Reviewed-on: https://go-review.googlesource.com/26890
Run-TryBot: Michael Hudson-Doyle <michael.hudson@canonical.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Crawshaw <crawshaw@golang.org>